Animal studies have shown that reducing the number of calories consumed extends the lifespan and slows the development of aging-related diseases. Studies of caloric restriction in humans have been limited in the past, but the National Institute on Aging is currently supporting a two- year study of healthy young men and women in which some will have a normal diet and others will consume 25% fewer calories. Samples of blood, urine, and tissue will be collected so that researchers can look for differences that may develop between the two groups. More specifically, researchers will be determining whether changes that have been observed in people living long, healthy lives are found in the volunteers who consume fewer calories. The study plan calls for extra samples to be collected, and this project would provide for a repository of freezers and liquid nitrogen storage units in which the extra samples would be stored for future testing. This repository will be a valuable research resource, as the frozen samples will be available for testing new ideas about aging and for using new testing techniques that will be developed during and after the study. Previous studies have shown that testing performed on frozen samples is valid, and repositories of frozen samples associated with studies of various types have proven useful to researchers even 15 or more years after the samples were originally collected. This project would support the maintenance and operation of the repository, covering the costs of temperature monitoring alarms, back-up power for the freezers, security for the repository, and record-keeping. Additionally, this project will support the salaries of repository staff members who will work with researchers to determine whether these frozen samples would be useful in their research and whether appropriate samples are available. When a researcher's request for samples is approved, repository personnel will carefully determine which samples to remove from the repository, pack them appropriately, ship them to the researcher's laboratory, and update the repository records. Having a repository of samples from this study will assist researchers as they try to determine whether cutting calories leads to changes in body chemistry that have been observed in healthy older people. If this is generally true, then people would want consider reducing their calorie intake as a way to increase their chances of living longer and being healthy as they age.